Technology

Kroon Hall

New Haven, Conn./Hopkins Architects

Green design is an attractive alternative these days. But given the eco-friendly mission of the School of Forestry and Environmental Studies at Yale University in New Haven, Conn., building green was not an option. It was an imperative. In planning their new $33.5 million building, school administrators not only sought to create a healthy place to study and work, they also wanted to bridge the gap between nature and people, deep in the heart of the city. That goal was met with aplomb by Hopkins Architects, of London, whose Kroon Hall—designed to consume half the energy of an equivalent academic building and reduce greenhouse gas emissions by 62 percent—is targeted to achieve LEED Platinum.

A blend of optimal performance and good design, the new home to faculty offices and an environmental resource center cuts a contemporary image while fitting comfortably among the venerable landmarks of Yale. “The challenge was to convert a backyard into a nice place,” says Hopkins director Michael Taylor. A gas-fired power plant, parking lot, and assorted dumpsters were removed from the site, replaced by the new academic center and two courtyards that knit the campus together. “That’s a big win,” Taylor adds.

Working with executive architect
Centerbrook Architects and Planners and sustainability consultant Atelier Ten, Hopkins created a 58,000-square-foot facility whose tall, narrow shape and east-west orientation reinforce the active and passive strategies used to heat and cool it. The lowest floor is set into a hillside, with only its south side exposed, providing thermal insulation and increasing the amount of natural light that enters the building from adjacent courtyards. A south-facing colonnade encourages activity to spill outside.

Thick walls of Briar Hill sandstone on the north and south façades have operable, high-performance windows set deep within precast concrete surrounds to shade from summer sun. Raised above the walls is a barnlike roof supported by arched frames of laminated Douglas fir. The roofline, lined in red oak (half of which comes from Yale’s own forests), creates a third-floor loft that houses an auditorium, two classrooms, a café, and a large common room.

As part of the design process, the team evaluated some 25 different sustainable measures to determine which were most cost- and energy-efficient. A 100-kilowatt photovoltaic array on the rooftop proved most desirable. It supplies 25 percent of the building’s electrical need. (The remaining electricity will be purchased from renewable sources, allowing the building to meet its goal of carbon neutrality.) In addition, four solar panels embedded in the southern façades help provide the building with hot water. Heating and cooling is provided by ground-source heat pumps that draw water from four 1,500-foot-deep wells near the building.

Integral to the building’s design is a displacement ventilation system that moves air through a plenum and into occupied spaces through diffusers in the raised floors. Low-velocity fans in the basement keep the air circulating almost imperceptibly. Fresh air is fed into the building through this system in summer and winter. But in spring and fall the mechanical systems are shut down, and occupants (prompted by color-coded lights) open the windows for ventilation.

A rainwater harvesting system channels water from the roof and grounds to a garden in the south courtyard, where aquatic plants filter out sediment and contaminants. The graywater is then used for landscape irrigation or pumped back into Kroon Hall for flushing toilets. In tandem with low-flow fixtures, the system is expected to save more than 500,000 gallons of potable city water per year.

Just four years ago, Yale President Richard Levin pledged to achieve a 43 percent reduction in Yale’s greenhouse gas emissions by 2020. With the completion of Kroon Hall, the most sustainable building on campus, the university has taken concrete steps to achieve that goal.